Z-019. Genotypic Characterization of O113 Shiga Toxin-Producing Escherichia coli (STEC) strains Isolated from Healthy Cattle of Northwest Sub-Region, Rio de Janeiro State, Brazil
Background: Ruminants (especially cattle) are animal reservoirs of Shiga toxin- producing Escherichia coli (STEC) strains that cause human illnesses since mild diarrhea until hemorrhagic colitis and hemolytic uremic syndrome (HUS). The serotype O113: H21 has been isolated of patients with HUS and presents a high occurrence in animals. Although frequently isolated in Brazil from animal sources this serotype was not yet detected in human clinical cases. Objective: Carry a genotypic characterization of thirteen STEC rfbO113 positive isolates previously recovered from five animals (two farms) in a longitudinal study (one year) with healthy cattle of Northwest Sub-region of Rio de Janeiro State, Brazil, in order to determine their virulence profile and maintenance in the host. Methods: The occurrence of chromosomal-encoded genes stx1, stx2, stx2c, stx2d, stx2f, iha, escC, escJ, irp2 and plasmidial-encoded genes saa, espP, ehxA, toxB, pilS, subA was searched through PCR assays. Results: A high diversity in the virulence genes patterns was detected. All isolates were positive for stx2 gene and three were also positive for stx1 gene. Five strains were positive for stx2c gene. Seven isolates were simultaneously positive for genes saa and espP and there were two isolates positive only for espP. Just three isolates were negative for pilS and iha. Three isolates were positive for irp2 gene and only one was negative for subA gene. No isolate was positive for stx2d, stx2f, toxB, escC and escJ genes. All isolates were positive for ehxA gene. Taken together, ten distinct virulence patterns were detected. Nevertheless, all but one strain presented the simultaneous presence of several virulence genes reinforcing their potential pathogenic role for humans. Conclusion: The data obtained in this work revealed that the probably O113 STEC isolates, even recovered from the same animal or farm, are a heterogeneous group. The common presence of STEC O113: H21 in the animal reservoir represents a risk that does not have to be neglected; otherwise, broader inquiries must be carried out to search of lineages of greater pathogenicity.
260/Z. Pathogenic Mechanisms, Host Response and Antimicrobial Susceptibility Testing of Animal Pathogens
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